Strong craving (4)
I believe the answer is:
urge
'strong craving' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for urge that I've seen before include "Encourage to proceed, drive onward" , "Encourage to go on, goad" , "Try hard to persuade, advise earnestly" , "Yen" , "Press to take action" .)